Specific antisocial and borderline personality disorder criteria and general substance use: A twin study

Antisocial (ASPD) and borderline (BPD) personality disorders (PDs) are associated with increased risk for substance use. They are "specific" risk factors among PDs in that they withstand adjusting for the other PDs, whereas the reverse does not hold. Specificity is a classic sign of causation. This empirical work addresses 3 further problems that can undermine causal inferences in personality and substance-use research: hierarchical nature of etiologic factors in psychiatry, imperfectly operationalized PD criteria, and possible genetic or environmental confounding, as seen in lack of "etiologic continuity." We used exploratory structural equation bifactor modeling and biometric models to mitigate these problems. The participants were Norwegian adult twins of ages 19-36 years (N = 2,801). Criteria for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), PDs were assessed using a structured interview. General substance-use risk was indicated by World Health Organization Composite International Diagnostic Interviewed alcohol use disorder and illicit drug use, and by self-reported regular smoking. A general risk factor for all criteria of both ASPD and BPD was the strongest individual correlate of general substance use and showed etiologic continuity, though just 3 specific PD criteria could predict substance use to the same extent. The findings indicate that a broad latent factor for both ASPD and BPD may be a specific and a genetically and environmentally unconfounded risk factor for substance use. Substance-use treatment research might benefit from attending to transdiagnostic models of ASPD, BPD, and related behavioral disinhibition. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Identification of Genetic Loci Shared Between Attention-Deficit/Hyperactivity Disorder, Intelligence, and Educational Attainment

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that is consistently associated with lower levels of educational attainment. A recent large genome-wide association study identified common gene variants associated with ADHD, but most of the genetic architecture remains unknown.

METHODS

We analyzed independent genome-wide association study summary statistics for ADHD (19,099 cases and 34,194 controls), educational attainment (N = 842,499), and general intelligence (N = 269,867) using a conditional/conjunctional false discovery rate (FDR) statistical framework that increases power of discovery by conditioning the FDR on overlapping associations. The genetic variants identified were characterized in terms of function, expression, and biological processes.

RESULTS

We identified 58 linkage disequilibrium-independent ADHD-associated loci (conditional FDR < 0.01), of which 30 were shared between ADHD and educational attainment or general intelligence (conjunctional FDR < 0.01) and 46 were novel risk loci for ADHD.

CONCLUSIONS

These results expand on previous genetic and epidemiological studies and support the hypothesis of a shared genetic basis between these phenotypes. Although the clinical utility of the identified loci remains to be determined, they can be used as resources to guide future studies aiming to disentangle the complex etiologies of ADHD, educational attainment, and general intelligence.

Associations between urine phthalate metabolites and thyroid function in pregnant women and the influence of iodine status

BACKGROUND

Human populations, including susceptible subpopulations such as pregnant women and their fetuses, are continuously exposed to phthalates. Phthalates may affect the thyroid hormone system, causing concern for pregnancy health, birth outcomes and child development. Few studies have investigated the joint effect of phthalates on thyroid function in pregnant women, although they are present as a mixture with highly inter-correlated compounds. Additionally, no studies have investigated if the key nutrient for thyroid health, iodine, modifies these relationships.

METHODS

In this study, we examined the cross-sectional relationships between concentrations of 12 urinary phthalate metabolites and 6 plasma thyroid function biomarkers measured mid-pregnancy (~17 week gestation) in pregnant women (N = 1072), that were selected from a population-based prospective birth cohort, The Norwegian Mother, Father and Child Cohort study (MoBa). We investigated if the phthalate metabolite-thyroid function biomarker associations differed by iodine status by using a validated estimate of habitual dietary iodine intake based on a food frequency questionnaire from the 22nd gestation week. We accounted for the phthalate metabolite mixture by factor analyses, ultimately reducing the exposure into two uncorrelated factors. These factors were used as predictors in multivariable adjusted linear regression models with thyroid function biomarkers as the outcomes.

RESULTS

Factor 1, which included high loadings for mono-iso-butyl phthalate (MiBP), mono-n-butyl phthalate (MnBP), and monobenzyl phthalate (MBzP), was associated with increased total triiodothyronine (TT3) and free T3 index (fT3i). These associations appeared to be driven primarily by women with low iodine intake (<150 µg/day, ~70% of our sample). Iodine intake significantly modified (p-interaction < 0.05) the association of factor 1 with thyroid stimulating hormone (TSH), total thyroxine (TT4) and free T4 index (fT4i), such that only among women in the high iodine intake category (≥150 µg/day, i.e. sufficient) was this factor associated with increased TSH and decreased TT4 and FT4i, respectively. In contrast, factor 2, which included high loadings for di-2-ethylhexyl phthalate metabolites (∑DEHP) and di-iso-nonyl phthalate metabolites (∑DiNP), was associated with a decrease in TT3 and fT3i, which appeared fairly uniform across iodine intake categories.

CONCLUSION

We find that phthalate exposure is associated with thyroid function in mid-pregnancy among Norwegian women, and that iodine intake, which is essential for thyroid health, could influence some of these relationships.

Maternal Drinking and Child Emotional and Behavior Problems

BACKGROUND AND OBJECTIVES

Maternal drinking is associated with child emotional and behavior problems. There is, however, a lack of studies that properly account for confounding. Our objective was to estimate the association between at-risk drinking in mothers of young children and child emotional and behavior problems, taking into account the passive transmission of familial risk.

METHODS

This population-based sample consists of 34 039 children nested within 21 911 nuclear families and 18 158 extended families from the Norwegian Mother, Father, and Child Cohort Study. Participants were recruited between 1999 and 2009 during routine ultrasound examinations. Data were collected during the 17th and 30th gestational week and when the children were 1.5, 3, and 5 years old. We applied a multilevel structural equation model that accounted for unobserved familial risks.

RESULTS

Children of mothers with at-risk drinking had a higher likelihood of behavior problems (β = 3.53; 95% confidence interval [CI] 3.01 to 4.05) than children of mothers with low alcohol consumption. This association was reduced after adjusting for factors in the extended family (β = 1.93; 95% CI 1.16 to 2.71) and the nuclear family (β = 1.20; 95% CI 0.39 to 2.01). Maternal at-risk drinking had a smaller association with child emotional problems (β = 1.80; 95% CI 1.26 to 2.34). This association was reduced after adjusting for factors in the extended family (β = 0.67; 95% CI -0.12 to 1.46) and the nuclear family (β = 0.58; 95% CI -0.31 to 1.48).

CONCLUSIONS

The results suggest an association between maternal at-risk drinking and child behavior problems. A reduction in maternal drinking may improve outcomes for children with such symptoms.

Nationwide Study of Neuropsychiatric Comorbidity and Medicines Use in Children With Autism Spectrum Disorder in Norway

Purpose: Autism spectrum disorder (ASD) has a high rate of comorbidity. While many children with ASD are exposed to psychotropic medicines, their efficacy and safety in these patients are unclear. There is a need for more detailed knowledge on which medicines are most commonly used and for which disorders. We aimed to investigate (a) prevalence and incidence rate of ASD among Norwegian children, and further, among newly diagnosed ASD children in 2014, study the (b) co-occurrence of neuropsychiatric disorders, (c) use of psychotropic drugs, and (d) the relationship between co-occurring diagnoses and use of psychotropic drugs. Method: Nationwide registry-based study of children 2-17 years old in Norway. Results: The ASD prevalence was 0.76% and the incidence rate was 0.12% in 2014. Of the children who received an initial ASD diagnosis in 2014 (n = 1,234), 64.8% had one or more co-occurring neuropsychiatric diagnosis. Psychotropic medication use was moderate (~20% used stimulants or hypnotics) in general, and low in children without comorbidity (nearly only hypnotics). There was a good accordance between co-occurring diagnoses and indication for the prescribed medications. Conclusions: Children with newly diagnosed ASD mainly received psychotropic drugs to treat co-occurring neuropsychiatric conditions.

Tourette syndrome in children in Norway

BACKGROUND

Tourette syndrome first appears in childhood and is characterised by chronic motor and vocal tics. In other countries, the mean prevalence is estimated at 0.77 % in children aged 6-15 years. Diagnostic practice and treatment have not been investigated in Norway.

MATERIAL AND METHOD

We used data retrieved from the Norwegian Patient Registry and the National Registry to calculate the percentage of children born during the period 2002-10 diagnosed with Tourette syndrome. The calculations were made for the country as a whole as well as by county. Drug therapy was investigated using data from the Norwegian Prescription Database.

RESULTS

By the age of 12, altogether 0.43 % had received a diagnosis of Tourette syndrome, broken down into 0.71 % for boys and 0.15 % for girls. The overall percentage varied from 0.15 % to 1.23 % between the counties. For Norway as a whole, the percentage of diagnoses remained stable between 2008 and 2016. Psychiatric and neurological conditions were often present - the most common being hyperkinetic disorder (50 %) and autism spectrum disorder (11 %). Antipsychotic drugs, probably for the treatment of tics, were prescribed for 16 % in the year following the diagnosis.

INTERPRETATION

The percentage of children with a diagnosis of Tourette syndrome is lower than the mean prevalence in population studies internationally. The diagnostic practice varies considerably from county to county.

Studies from the Norwegian Twin Registry on risk factors for health related work incapacity

Background

For the past decade, researchers from the Nordic countries have taken the advantage of their large twin cohorts and reliable official registries to deepen our understanding of sick leave and disability pension. This presentation will give a brief summary of studies based on data from The Norwegian Twin Registry (NTR).

Methods

Monozygotic twins develop from one fertilized egg cell and are genetically identical, while dizygotic twins are the result of two fertilized egg cells and share, as ordinary siblings, in average 50% of their segregating genes. With data from large cohorts of twins reared together, it is possible to calculate the proportion of variance in an outcome that stems from genetic, shared and non-shared environmental factors respectively. Furthermore, when exploring the contribution from measured risk factors on specific outcomes, adjustment for unmeasured confounders (genes and shared environment) can bring us closer to determine causality in epidemiological studies. Both methods were applied in our studies. NTR now includes data from about 30 000 twins, but until recently we focused on a subsample of about 8 000 young adults (born 1967-1979). Data from questionnaires and interviews were linked to registries on sick leave and disability pension.

Results

In line with previous studies, we found that the liability to sick leave and disability pensioning, as well as the transition from the former to the latter, was strongly to moderately influenced by genetic factors. We found no evidence for “social transmission”, e.g. that environmental factors shared by the twins contributed to these outcomes. Further details and results from studies on measured risk factors, with emphasize on mental health, will be presented at the conference.

Conclusions

Twin studies cast light on different aspects of work incapacity, including reducing stigma such as those associated with theories of social transmission of health related benefits.

Education, lifestyle and life course differences in level of work incapacity – genes and environment

Background

As many countries face an aging workforce, it is becoming ever more relevant to understand the underlying causes of work incapacity across the entire working age. Previous twin studies have demonstrated that work incapacity is influenced by genetic as well as environmental factors. Furthermore, educational attainment and lifestyle behaviors are relatively stable from early adulthood and are associated with work incapacity. This association may be confounded by unobserved factors - both genetic and environmental. In two separate twin studies, we examine 1) the stability and change in genetic and environmental factors influencing work incapacity from age 18 until retirement, and sex differences in these effects, and 2) the associations and likelihood of causality between educational attainment, lifestyle and sickness absence.

Methods

study 1: A population-based sample of 28,759 twins were linked to high quality national registry data and followed for up to 23 years. We measured work incapacity as the total proportion of potential workdays lost due to sickness absence, rehabilitation, and disability benefits.

study 2: Data from a subsample of 8,806 twins who completed health questionnaires were linked to registry data on sickness absence and educational attainment. Self-reported lifestyle behaviors were smoking, physical activity and BMI (height and weight).

Results

study 1: Structural equation modeling indicated moderate genetic influences on work incapacity throughout life in both men and women, with a high degree of genetic stability from young to old adulthood.

study 2: Preliminary regression analyses indicated that genetic factors largely confound the associations between educational attainment, lifestyle and sickness absence.

Conclusions

Genetic factors seem to be a major issue in understanding causes of work incapacity. Largely the same genetic factors influence individual differences in work incapacity throughout working age.

Continuity of genetic and environmental influences on clinically assessed major depression from ages 18 to 45

BACKGROUND

Studies on the stability of genetic risk for depression have relied on self-reported symptoms rather than diagnoses and/or short follow-up time. Our aim is to determine to what degree genetic and environmental influences on clinically assessed major depressive disorder (MDD) are stable between age 18 and 45.

METHODS

A population-based sample of 11 727 twins (6875 women) born between 1967 and 1991 was followed from 2006 to 2015 in health registry data from primary care that included diagnoses provided by treating physicians. Individuals with schizophrenia or bipolar disorder (n = 163) were excluded. We modelled genetic and environmental risk factors for MDD in an accelerated longitudinal design.

RESULTS

The best-fitting model indicated that genetic influences on MDD were completely stable from ages 18 to 45 and explained 38% of the variance. At each age, the environmental risk of MDD was determined by the risk at the preceding observation, plus new environmental risk, with an environmental correlation of +0.60 over 2 years. The model indicated no effects of shared environment and no environmental effects stable throughout the observational period. All long-term stability was therefore explained by genetic factors.

CONCLUSIONS

Different processes unfolded in the genetic and environmental risk for MDD. The genetic component is stable from later adolescence to middle adulthood and accounted for nearly all long-term stability. Therefore, molecular genetic studies can use age-heterogenous samples when investigating genetic risk variants of MDD. Environmental risk factors were stable over a short span of years with associations rapidly decreasing and no evidence of permanent environmental scarring.

Attention-deficit hyperactivity disorder shares copy number variant risk with schizophrenia and autism spectrum disorder

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable common childhood-onset neurodevelopmental disorder. Some rare copy number variations (CNVs) affect multiple neurodevelopmental disorders such as intellectual disability, autism spectrum disorders (ASD), schizophrenia and ADHD. The aim of this study is to determine to what extent ADHD shares high risk CNV alleles with schizophrenia and ASD. We compiled 19 neuropsychiatric CNVs and test 14, with sufficient power, for association with ADHD in Icelandic and Norwegian samples. Eight associate with ADHD; deletions at 2p16.3 (NRXN1), 15q11.2, 15q13.3 (BP4 & BP4.5-BP5) and 22q11.21, and duplications at 1q21.1 distal, 16p11.2 proximal, 16p13.11 and 22q11.21. Six of the CNVs have not been associated with ADHD before. As a group, the 19 CNVs associate with ADHD (OR = 2.43, P = 1.6 × 10^-21), even when comorbid ASD and schizophrenia are excluded from the sample. These results highlight the pleiotropic effect of the neuropsychiatric CNVs and add evidence for ADHD, ASD and schizophrenia being related neurodevelopmental disorders rather than distinct entities.

Diagnosing autism spectrum disorder among children in Norway

BACKGROUND

The percentage share of children who are diagnosed with autism spectrum disorder has increased considerably since the 1990s in Norway as well as in other countries. It has previously been demonstrated that there is considerable variation between counties with respect to diagnostic practice.

MATERIAL AND METHOD

We calculated the percentage of children with autism spectrum disorder by using patient data obtained from the Norwegian Patient Registry and population data obtained from the National Registry. The calculations were made for the country as a whole as well as by county. The diagnostic assessments and documentation were mapped by linking the Norwegian Patient Registry with the Norwegian Mother, Father and Child Cohort study. We also reviewed patient records obtained from the specialist health service and considered whether diagnostic practice satisfied the research criteria for autism spectrum disorder.

RESULTS

By the age of eight, 1.1 % of boys and 0.3 % of girls had been diagnosed with autism spectrum disorder. The overall percentages varied from 0.3 to 1.0 between counties. From 2008 to 2016, these percentages increased in all age groups. Our review of patient records included 503 children. In 95 % of cases the patient records provided a high standard of documentation that the diagnostic research criteria had been satisfied. The assessments were largely conducted in accordance with the guidelines drawn up by the various health trusts.

INTERPRETATION

Autism diagnoses are generally well documented within the Norwegian specialist health service and meet the diagnostic criteria. In the counties that demonstrate a low prevalence of autism, it appears the health service fails to recognise autism in many children, particularly girls, or the diagnosis is determined late.

Joint factorial structure of psychopathology and personality

BACKGROUND

Normative and pathological personality traits have rarely been integrated into a joint large-scale structural analysis with psychiatric disorders, although a recent study suggested they entail a common individual differences continuum.

METHODS

We explored the joint factor structure of 11 psychiatric disorders, five personality-disorder trait domains (DSM-5 Section III), and five normative personality trait domains (the 'Big Five') in a population-based sample of 2796 Norwegian twins, aged 19‒46.

RESULTS

Three factors could be interpreted: (i) a general risk factor for all psychopathology, (ii) a risk factor specific to internalizing disorders and traits, and (iii) a risk factor specific to externalizing disorders and traits. Heritability estimates for the three risk factor scores were 48% (95% CI 41‒54%), 35% (CI 28‒42%), and 37% (CI 31‒44%), respectively. All 11 disorders had uniform loadings on the general factor (congruence coefficient of 0.991 with uniformity). Ignoring sign and excluding the openness trait, this uniformity of factor loadings held for all the personality trait domains and all disorders (congruence 0.983).

CONCLUSIONS

Based on our findings, future research should investigate joint etiologic and transdiagnostic models for normative and pathological personality and other psychopathology.

Bias from self selection and loss to follow-up in prospective cohort studies

Self-selection into prospective cohort studies and loss to follow-up can cause biased exposure-outcome association estimates. Previous investigations illustrated that such biases can be small in large prospective cohort studies. The structural approach to selection bias shows that general statements about bias are not possible for studies that investigate multiple exposures and outcomes, and that inverse probability of participation weighting (IPPW) but not adjustment for participation predictors generally reduces bias from self-selection and loss to follow-up. We propose to substantiate assumptions in structural models of selection bias through calculation of genetic correlations coefficients between participation predictors, outcome, and exposure, and to estimate a lower bound for bias due to self-selection and loss to follow-up by comparing effect estimates from IPP weighted and unweighted analyses. This study used data from the Norwegian Mother and Child Cohort Study and the Medical Birth Registry of Norway. Using the example of risk factors for ADHD, we find that genetic correlations between participation predictors, exposures, and outcome suggest the presence of bias. The comparison of exposure-outcome associations from regressions with and without IPPW revealed meaningful deviations. Assessment of selection bias for entire multi-exposure multi-outcome cohort studies is not possible. Instead, it has to be assessed and controlled on a case-by-case basis.

Association of Maternal Neurodevelopmental Risk Alleles With Early-Life Exposures

Importance

Early-life exposures, such as prenatal maternal lifestyle, illnesses, nutritional deficiencies, toxin levels, and adverse birth events, have long been considered potential risk factors for neurodevelopmental disorders in offspring. However, maternal genetic factors could be confounding the association between early-life exposures and neurodevelopmental outcomes in offspring, which makes inferring a causal relationship problematic.

Objective

To test whether maternal polygenic risk scores (PRSs) for neurodevelopmental disorders were associated with early-life exposures previously linked to the disorders.

Design, Setting, and Participants

In this UK population-based cohort study, 7921 mothers with genotype data from the Avon Longitudinal Study of Parents and Children (ALSPAC) underwent testing for association of maternal PRS for attention-deficit/hyperactivity disorder (ADHD PRS), autism spectrum disorder (ASD PRS), and schizophrenia (SCZ PRS) with 32 early-life exposures. ALSPAC data collection began September 6, 1990, and is ongoing. Data were analyzed for the current study from April 1 to September 1, 2018.

Exposures

Maternal ADHD PRS, ASD PRS, and SCZ PRS were calculated using discovery effect size estimates from the largest available genome-wide association study and a significance threshold of P < .05.

Main Outcomes and Measures

Outcomes measured included questionnaire data on maternal lifestyle and behavior (eg, smoking, alcohol consumption, body mass index, and maternal age), maternal use of nutritional supplements and medications in pregnancy (eg, acetaminophen, iron, zinc, folic acid, and vitamins), maternal illnesses (eg, diabetes, hypertension, rheumatism, psoriasis, and depression), and perinatal factors (eg, birth weight, preterm birth, and cesarean delivery).

Results

Maternal PRSs were available from 7921 mothers (mean [SD] age, 28.5 [4.8] years). The ADHD PRS was associated with multiple prenatal factors, including infections (odds ratio [OR], 1.11; 95% CI, 1.04-1.18), use of acetaminophen during late pregnancy (OR, 1.11; 95% CI, 1.04-1.18), lower blood levels of mercury (β coefficient, -0.06; 95% CI, -0.11 to -0.02), and higher blood levels of cadmium (β coefficient, 0.07; 95% CI, 0.05-0.09). Little evidence of associations between ASD PRS or SCZ PRS and prenatal factors or of association between any of the PRSs and adverse birth events was found. Sensitivity analyses revealed consistent results.

Conclusions and Relevance

These findings suggest that maternal risk alleles for neurodevelopmental disorders, primarily ADHD, are associated with some pregnancy-related exposures. These findings highlight the need to carefully account for potential genetic confounding and triangulate evidence from different approaches when assessing the effects of prenatal exposures on neurodevelopmental disorders in offspring.

Genome-wide association study identifies eight risk loci and implicates metabo-psychiatric origins for anorexia nervosa

Characterized primarily by a low body-mass index, anorexia nervosa is a complex and serious illness1, affecting 0.9-4% of women and 0.3% of men2-4, with twin-based heritability estimates of 50-60%5. Mortality rates are higher than those in other psychiatric disorders6, and outcomes are unacceptably poor7. Here we combine data from the Anorexia Nervosa Genetics Initiative (ANGI)8,9 and the Eating Disorders Working Group of the Psychiatric Genomics Consortium (PGC-ED) and conduct a genome-wide association study of 16,992 cases of anorexia nervosa and 55,525 controls, identifying eight significant loci. The genetic architecture of anorexia nervosa mirrors its clinical presentation, showing significant genetic correlations with psychiatric disorders, physical activity, and metabolic (including glycemic), lipid and anthropometric traits, independent of the effects of common variants associated with body-mass index. These results further encourage a reconceptualization of anorexia nervosa as a metabo-psychiatric disorder. Elucidating the metabolic component is a critical direction for future research, and paying attention to both psychiatric and metabolic components may be key to improving outcomes.

The structure of genetic and environmental influences on normative personality, abnormal personality traits, and personality disorder symptoms

BACKGROUND

Can the structure of genetic and environmental influences on normative personality traits (NPTs), abnormal personality traits (APTs), and DSM-IV criteria for personality disorders (PD) fit a high or low congruence model positing, respectively, close or more limited etiologic continuity?

METHOD

Exploratory factor analysis was applied to transformed correlation matrices from Cholesky twin decompositions obtained in OpenMx. In 2801 adult twins from the Norwegian Institute of Public Health Twin Panel, NPTs and APTs were assessed by self-report using the Big Five Inventory (BFI) and PID-5-Norwegian Brief Form (PID-5-NBF), respectively. PDs were assessed at interview using the Structured Interview for DSM-IV Personality (SIDP-IV).

RESULTS

The best model yielded three genetic and three unique environmental factors. Genetic factors were dominated, respectively, by (i) high loadings on nearly all PDs and NPT/APT neuroticism and compulsivity, (ii) negative loadings on NPT agreeableness/conscientiousness and positive loadings on APT/PD measures of antisocial traits, and (iii) negative loadings on NPT extraversion and histrionic PD, and positive loadings on APT detachment and schizoid/avoidant PD. Unique environmental factors were dominated, by (i) high loadings on all PDs, (ii) high loadings on all APT dimensions and NPT neuroticism, and (iii) negative loadings on NPT extraversion and positive loadings on NPT detachment/avoidant PD.

CONCLUSIONS

Two genetic and one environmental common factor were consistent with a high congruence model while one genetic and two environmental factors were more supportive of a low congruence model. The relationship between genetic and environmental influences on personality assessed by NPTs, APTs, and PDs is complex and does not fit easily into a low or high congruence model.

Relationships Among Avoidant Personality Disorder, Social Anxiety Disorder, and Normative Personality Traits: A Twin Study

Avoidant personality disorder (AvPD) and social anxiety disorder (SAD) share risk factors to a substantial degree, and both are characterized by the experience of anxiety in social situations. The authors investigated whether these disorders are differentially related to the Big Five personality traits. They also examined the underlying genetic and environmental influences on these associations. A population-based sample of 1,761 female twins was interviewed at baseline, and 1,471 of these were re-interviewed 10 years later. Associations between AvPD, SAD, and personality traits were investigated with multivariate biometric analyses. The authors found that AvPD and SAD are differentially related to several personality traits at the phenotypic, genetic, and environmental level. The genetic and environmental liability to AvPD could be fully accounted for by the genetic and environmental factors influencing SAD and personality. The findings may increase current etiological understanding of these disorders and inform future classification and treatment efforts.

Explaining the association between anxiety disorders and alcohol use disorder: A twin study

BACKGROUND

It is unknown whether social anxiety disorder (SAD) has a unique association with alcohol use disorder (AUD) over and beyond that of other anxiety disorders, how the associations develop over time, and whether the associations are likely to be causal.

METHODS

Diagnoses of AUD, SAD, generalized anxiety disorder, panic disorder, agoraphobia, and specific phobias were assessed twice using the Composite International Diagnostic Interview among 2,801 adult Norwegian twins. The data were analyzed using logistic regression analyses and multivariate biometric structural equation modeling.

RESULTS

SAD had the strongest association with AUD, and SAD predicted AUD over and above the effect of other anxiety disorders. In addition, SAD was prospectively associated with AUD, whereas other anxiety disorders were not. AUD was associated with a slightly elevated risk of later anxiety disorders other than SAD. Biometric modeling favored a model where SAD influenced AUD compared to models where the relationship was reversed or due to correlated risk factors. Positive associations between AUD and other anxiety disorders were fully explained by shared genetic risk factors.

CONCLUSIONS

Unlike other anxiety disorders, SAD plausibly has a direct effect on AUD. Interventions aimed at prevention or treatment of SAD may have an additional beneficial effect of preventing AUD, whereas interventions aimed at other anxiety disorders are unlikely to have a similar sequential effect on AUD.

Prenatal and perinatal risk factors for eating disorders in women: A population cohort study

OBJECTIVE

The fetal programming model hypothesizes that developmental programming in utero and in early life induces adaptations that predetermine the adult phenotype. This study investigated whether prenatal/perinatal complications are associated with lifetime eating disorders in women.

METHOD

Participants included 46,373 adult women enrolled in the Norwegian Mother and Child Cohort Study (den norske Mor & barn-undersøkelsen [MoBa]). MoBa mothers and their mothers (MoBa grandmothers) were the focus of the current study. MoBa mothers with lifetime eating disorders were compared to a referent group.

RESULTS

MoBa mothers who weighed more at birth (birth weight, adjusted odds ratio [OR] = 1.14; 95% confidence interval [CI]: 1.10-1.19) or were born large-for-gestational-age (adjusted OR = 1.39; 95% CI: 1.27-1.52) were more likely to develop binge-eating disorder in later life. MoBa mothers who weighed less at birth were more likely to develop anorexia nervosa (birth weight, adjusted OR = 0.88; 95% CI: 0.81-0.95). Bulimia nervosa and purging disorder (PD) were not significantly predicted by the prenatal and perinatal factors examined.

DISCUSSION

Results of this study, which include the first known investigation of prenatal and perinatal factors in binge-eating disorder and PD, suggest that fetal programming may be relevant to the development of anorexia nervosa and binge-eating disorder. Future genetically informative research is needed to help disentangle whether these associations are a function of genetic influences or a true environmental fetal programming effect.

Is the association between maternal alcohol consumption in pregnancy and pre-school child behavioural and emotional problems causal? Multiple approaches for controlling unmeasured confounding

BACKGROUND AND AIMS

Hazardous drinking (i.e. alcohol consumption that places drinkers at risk for adverse health outcomes) during pregnancy is associated with adverse child outcomes. To address whether the associations are causal, we aimed to estimate the effect of maternal hazardous drinking during the first trimester on offspring emotional and behavioural problems throughout the pre-school age. We adjusted for: (1) measured confounding (e.g. smoking), (2) familial risk factors by sibling control design and (3) non-shared environmental risk factors by using hazardous drinking the 3 months before pregnancy as an instrumental variable.

DESIGN

Prospective cohort study. Participants were recruited between 1999 and 2009 at ultrasound examination offered to all pregnant women in Norway. Data were collected during the 17th and the 30th weeks of gestation, and when the children were aged 1.5, 3 and 5 years.

SETTING

Norway, 1999-2015.

PARTICIPANTS

The sample consisted of 14 639 mothers with 25 744 offspring siblings from the Norwegian Mother and Child Cohort Study.

MEASUREMENTS

Respondents self-reported on: alcohol consumption, children's emotional problems (i.e. emotional reactive, anxiety/depression, somatic complaints) and children's behavioural problems (i.e. attention and aggressive behaviour) throughout pre-school age. We used longitudinal latent growth curve models to estimate the effect of maternal drinking during the first trimester on offspring emotional and behavioural problems.

FINDINGS

Most associations were strongly reduced after controlling for both familial and measured environmental risk factors. After adjustment, exposed children were more emotionally reactive [β = 2.33; 95% confidence interval (CI) = 0.13-4.53] and had more somatic complaints (β = 1.93; 95% CI = 0.09-3.77) at age 3, but not at age 5. Exposed children were less aggressive than unexposed siblings at age 5 (β = -2.27; 95% CI = -4.02 to -0.52).

CONCLUSIONS

Children exposed to their mothers' hazardous drinking during the first trimester appear to be more emotionally reactive and have more somatic complaints at age 3, but not at age 5, and are less aggressive at age 5 compared with unexposed siblings.

Sensitivity and specificity of early screening for autism

BACKGROUND

Early identification and diagnosis is beneficial for children with autism spectrum disorder (ASD). Universal early screening is recommended by many experts, but disputed because evidence is limited, and sensitivity and specificity in general populations are largely unknown.

AIMS

To estimate the sensitivity and specificity of early population-based screening for ASDs.

METHOD

The study was based on the Norwegian Mother and Child Cohort Study. The 36-month cohort questionnaire included the Social Communication Questionnaire (SCQ), a 40-item screening instrument for ASD.

RESULTS

A total of 58 520 mothers (58%) responded to the questionnaire. By the end of follow-up on 31 December 2015, 385 (0.7%) individuals with ASD had been identified among the responders' children. The distributions of SCQ scores in those with ASD and other children had large degrees of overlap. With the cut-off of 15 recommended in the SCQ manual, screening sensitivity was 20% (95% CI 16-24) for ASD overall. For children with ASD who had not developed phrase speech at 36 months, sensitivity was 46% (95% CI 35-57%), whereas it was 13% (95% CI 9-17) for children with ASD with phrase speech. Screening specificity was 99% (95% CI 99-99). With the currently recommended cut-off of 11, sensitivity increased to 42% for ASD overall (95% CI 37-47), 69% (95% CI 58-79) for ASD without phrase speech and 34% (95% CI 29-40) for ASD with phrase speech. Specificity was then reduced to 89% (95% CI 89-90).

CONCLUSIONS

Early ASD screening with a parent checklist had low sensitivity. It identified mainly individuals with ASD with significant developmental delay and captured very few children with ASD with cognitive skills in the normal range. Increasing sensitivity was not possible without severely compromising specificity.

DECLARATION OF INTEREST

C.L. receives royalty for the Social Communication Questionnaire, which she has co-authored.

Maternal Thyroid Function During Pregnancy or Neonatal Thyroid Function and Attention Deficit Hyperactivity Disorder: A Systematic Review

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioral disorder in children, yet its etiology is poorly understood. Early thyroid hormone disruption may contribute to the development of ADHD. Disrupted maternal thyroid hormone function has been associated with adverse neurodevelopmental outcomes in children. Among newborns, early-treated congenital hypothyroidism has been consistently associated with later cognitive deficits.

METHODS

We systematically reviewed literature on the association between maternal or neonatal thyroid hormones and ADHD diagnosis or symptoms. We searched Embase, Pubmed, Cinahl, PsycInfo, ERIC, Medline, Scopus, and Web of Science for articles published or available ahead of print as of April 2018.

RESULTS

We identified 28 eligible articles: 16 studies of maternal thyroid hormones, seven studies of early-treated congenital hypothyroidism, and five studies of neonatal thyroid hormones. The studies provide moderate evidence for an association between maternal thyroid hormone levels and offspring ADHD, some evidence for an association between early-treated congenital hypothyroidism and ADHD, and little evidence for an association between neonatal thyroid hormone levels and later ADHD.

CONCLUSIONS

The reviewed articles suggest an association between maternal thyroid function and ADHD, and possibly between early-treated congenital hypothyroidism and ADHD. Study limitations, however, weaken the conclusions in our systematic review, underlining the need for more research. Importantly, there was much variation in the measurement of thyroid hormone function and of ADHD symptoms. Recommendations for future research include using population-based designs, attending to measurement issues for thyroid hormones and ADHD, considering biologically relevant covariates (e.g., iodine intake), and assessing nonlinear dose-responses.

Adult ADHD Symptoms and Satisfaction With Life: Does Age and Sex Matter?

OBJECTIVE

To investigate adult ADHD symptoms and satisfaction with life, with a focus on age and sex differences.

METHOD

This study is based on parents in the Norwegian Mother and Child Cohort Study (MoBa). The Adult Self-Report Scale (ASRS-6) and Satisfaction With Life Scale (SWLS) scores were analyzed from 33,210 men and 41,983 women from young to middle adulthood.

RESULTS

Mean ASRS total score was significantly higher in men, where 5.1% scored above cutoff, compared with 2.9% in women. Factor loadings supported the two ASRS subscales: Inattention (Inatt) and Hyperactivity-Impulsivity (HyImp) in both sexes. A significant decline with age was found on HyImp, whereas Inatt scores were reasonably stable in men and u-curved in women. High ASRS scores were associated with lower SWLS, but poor satisfaction with life was found only in high-scoring women.

CONCLUSION

Our findings suggest caution to age and sex when using the ASRS-6.